Grid resistor structure



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GRID RESISTOR STRUCTURE Filed May 8, 1963 2 Sheets-Sheet l NN I; .r M L.W a

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United States Patent 3,191,138 GI-ill REEISTUR STRUQTURE David C.Wyeofii, Broohfieid, Wis, assignor to Harnischfeger Corporation,Milwaukee, Wis. Filed May S, 1%3, Ser. No. 273,871 9 Eliairns. (Qi.assear This invention relates to a resistor and more particularly to aresistor structure predicated upon a helical ribbon twist design.

Basically, the novel resistor structure comprises a grid which is formedfrom a resistive element twisted into a helical ribbon. Grids of thisnature could be stacked in a bank and connected in series or parallel asdesired by welding or clamping adjacent terminating ends of each gridtogether, with insulation means as required. Preferably, the helicalribbon twist grid is formed from a continuous strip of resistivematerial which is twisted into a first helical ribbon twist portion andis then bent backwards upon itself for twisting into a second helicalribbon twist portion. The said portions are parallelly aligned inintermeshing but non-contiguous relationship. In accordance with theinvention, it is possible to multiply this basic conception into allthree spatial dimensions whereby a bank of stacked and intertwinedhelical ribbon twist resistors may be formed.

It is an object of this invention to provide a novel resistor structurechmacterized by interrneshed helical ribbon twist portions.

It is another object of this invention to provide a resistor structurewhich exhibits enhanced ligidityg compaction; and heat dissipatingcharacteristics.

it is another object of this invention to provide a resistor structurewhich may be simply and expeditiously formed in an economical fashion.

It is yet another object of this invention to provide a resistorstructure characterized by a large surface area per unit length wherebyturbulence is induced in the movement of air about the resistorstructure.

It is still another object of this invention to provide a resistorstructure which is adapted for two or for three dimensional design overa whole range of series; parallel; or series-parallel interconnections.

These and other objects, advantages, and features of the subjectinvention will hereinafter appear, and, for purposes of illustration,but not of limitation, exemplary embodiments of the subject inventionare shown in the appended drawings, in which:

FIGURE 1 is a top plan view of a first embodiment of the inventionpredicated upon two helical ribbon twist portions;

FIGURE 2 is a front elevational view of the structure shown in FIGURE 1;

FIGURE 3 is an end elevational view of the structure shown in FIGURE 1,taken along the line 3--3 thereof;

FIGURE 4 is a schematic plan view of a bar of resistive material whichmay be suitably bent and fashioned into the structure shown in FIGURESl3;

FIGURE 5 is a sectional view taken along the line 5--5 of FIGURE 2; 1

FIGURE 6 is a top plan view of a second embodiment of the inventionshowing a continuous one piece grid resistor provided with fourparallelly aligned helical ribbon twist portions; and

FIGURE 7 is a front elevational view of two sets of resistor structuresof the type shown in FIGURE 6 mounted in stacked vertical alignment.

In its simplest form, the subject invention is exemplified by the dualhelical ribbon twist structure 2 shown in FIGURES 1-3. A bar 4 ofsuitable resistive material (such as resistor alloy materials ofthenickel-chromium June 22, 1965 or stainless steeltype) is suitably bentand twisted to form the structure shown in FIGURE 1. The bar 4 isrectangular in shape and comprises a front face F, a rear face R, a topedge T, and a bottom edge B. The F, R, T, and B reference characterdesignations are utilized hereinafter to designate these respectivesurfaces of the helical ribbon twist resistors.

As shown in FIGURE 1, a first tab portion 3 of the bar 4 defines one endof the resistor structure 2. The bar 4 is twisted to define the helicalribbon twist portion 6, which extends from the tab portion 3. The bar isthen bent into a U-shaped bridge member 8. The bridge member d has achanneled cross section as indicated by the concave base It whichdefines the trough space 12 in between the side flanges l4 and 1d. Thebar 4 is again twisted to form a similar ribbon twist portion 18 whichextends from the bridge member 3 in parallel alignment and inintermeshing but non-contiguous relationship with the first helicalribbon twist portion 6. The bar 4 then terminates in a tab portion 29which is aligned with the initial tab portion 3, as best indicated inFIGURE 1.

Means are provided on each of the tab portions 3 and 2% for connectingthe resistor structure 2 to a suitable source of electric potential. Inthe described embodiment, these means are illustrated schematically bythe weld joints tl and 92 which are respectively positioned [on the tabportions 3 and 20. As indicated in FIGURES 1 and 2, suitable leads 22and 24 are attached to the weld joints 9t) and 92 respectively in orderto effectuate the desired connection to the said source of electricpotential. If desired, another point for electrical connection can beprovided :on the bridge member 8, as indicated by the Weld joint 91,shown in FIGURES 1-3.

With the described connection points 9t992, it is possible to achieve avariety of electrical connections. For example, a potential impressedacross the points 99-92 will energize the resistive helical ribbon twistportions 6 and 18 in series. Likewise, an electrical potential impressedacross the points 9 3-91 will energize the helical ribbon twist portion6, and an electrical potential irripressed across the points it-92 willenergize the helical ribbon twist portion 18. Furthermore, when thepoints and 92 are suitably interconnected, a potential may be impressedacross the said common points9-92 and the point 91, such that thehelical ribbon twist portions 6 and 18 may be energized in parallel.

It should be apparent that the arrangement shown in FIGURE 1 providesfor horizontal stacking of similar helical ribbon twist portions (suchas the portions 6 and 18, which are horizontally stacked in the plane ofthe FIGURE 1 drawing). If desired, identical resistor structures 2 couldbe horizontally stacked in the plane of the FIGURE 1 drawing to anydesired extent. Also, the individual helical ribbon twist portions couldbe axially extended or diminished as desired. In actual practice, thetwist dimensions will vary dependent upon operating characteristicswhich are desired. In commercial embodiments, the resistor structure 2would not have as many twists per unit length nor would the helicalribbon twist portions be placed as closely together, as illustrated inthe drawings. However, for present purposes, the helical ribbon twistportions have been compacted in order to best illustrate schematicallythe nature of the subject invention. The helical ribbon twist portion 6is an ordinary helical or auger twist such that the locus of the edgeportions thereof define two intermeshing helices which have a commonaxis :of revolution indicated by the line AA of FIGURE 1.

While FIGURE 1 illustrates a horizontal stacking of helical ribbon twistportions (i.e., a coplanar disposition of the respective axes ofrevolution for the helical ribbon e.) twist portions 6 and 18), itshould be understood that similar grid resistor structures 2 may bevertically stacked as well (i.e., additional helical ribbon twistportions may be provided such that the axes of revolution thereof areparallelly aligned with the axes of revolution of the helical ribbontwist portions 6 and 18, but are disposed in a plane other than theplane of the axes of the portions 6 and 18).

This vertical stacking arrangement, as well as a further embodiment ofthe horizontal stacking arrangement, is illustrated by the embodiment ofthe invention designated by the numeral 32 and illustrated in theFIGURES 6 and 7. The grid resistor structure 32 generally corresponds tothe grid resistor structure 2 previously described, except that inessence it amounts to a duplication thereof. The rod 34 is provided witha first tab portion 33 and with front F and rear R faces and with top Tand bottom B edges, as indicated in FIGURE 6. The rod 34 is then bentinto a first helical ribbon twist portion 50 which extends from the tabportion 34. A bridge member 38a, generally corresponding to the bridgemember 8 of FIGURE 1, effects a reversal of direction of the bar 34,which is again twisted into a ribbon twist portion 52 which isparallelly aligned and in intermeshing but non-contiguous relationshipwith the first portion A second bridge member 386 then effects anotherreversal of the bar 34, which is then twisted into a third helicalribbon twist portion S t/which is intermeshed with the helical ribbontwist portion 52 in parallel alignment but non-contiguous relationship.A third bridge member 38b then efiects still another reversal of the bar34, which is similarlytwisted into the fourth helical ribbon twistportion 56 which is again parallelly aligned in intermeshing butnon-contiguous relationship with the third helical ribbon twist portion54. The helical ribbon twist portion 56 then terminates in the tabportion 6d, which corresponds to the tab portion of the FIGURE '1embodiment.

' Connection points 93 and )7 are provided on the tab portions 33 and 69respectively, and similarly connection points 94, 95, and 96 areprovided on the bridge members $851,380, and 38b respectively. TheFIGURE 6 structure thus represents a one piece continuous resistor unitcharacterized by four parallelly aligned helical ribbon twist portions,the axes of revolution of which are coplanar. Appropriate electricalconnections across the contact points 93-97 can serve to energize therespective helical ribbon twist portions 50, 52, 54, and 56 in anydesired series, parallel, or series-parallel relationship.

FIGURE 7 illustrates a vertical stacking of the grid resistor structure32 shown in FIGURE 6. A grid resistor structure 32', which is generallysimilar to the grid resistor structure 32, is juxtaposed thereto suchthat the coplanar axes of revolution for the four helical ribbon twistportions of the structure 32 are disposed in a plane which is parallelto the plane of the coplanar axes of revolution for the four helicalribbon twist portions of the structure 32. Corresponding connectionpoints are also provided for the bottom grid resistor structure 32, asindicated by the contact points 95, 96, and 97 for the helical ribbontwist portion 54' and 56' of the grid resistor structure 32'.

From the foregoing description, it should be apparent that banks ofresistor units may be formed by horizontal, vertical, or horizontal andvertical stacking. Also, each of the individual helical ribbon twistportions may be parts of one continuous resistive element which issuit-ably bent and fashioned into the desired orientation. It is alsopossible to form a three dimensional matrix of intermeshing helicalribbon twist resistors from a one piece resistive element, as forexample by bending the grid resistor structure 32 around the contactpoint 95 of the bridge member 38c such that the axes of revolution ofthe helical ribbon twist portions 50 and 52; 54 and 56; 52 and 54; and50 and 56 are respectively coplanar (i.e., the 56- 52 plane would beparallel with the 54-56 plane, and the 52-54 plane and the 50-56 planewouldeach be perpendicular to both of the 5tl-52 and the 54-56 planes).

It is also contemplated that the helical ribbon twist portions could bemade up in single pieces of any desired length and then stacked on rodsor mounted in any other suitable way with appropriate spacers andinsulations to form resistor units of the type described herein. Variousconventional means could be utilized to weld or clamp together therespective ends of such individual helical ribbon twist portions inorder to form a current resistive path defined by a horizontally,vertically, or horizontally and vertically aligned helical ribbon twiststacked arrangement, as heretofore described. Furthermore, the stackedresistor structures described herein could be mounted relative to afixed support in vertical, horizontal, or other dispositions, asrequired.

It should be understood that various changes, modifications, andalterations may be effected in the details of construction, operationand materials for the various elements, without departing from thespirit and the scope of the instant invention, as defined in theappended claims.

What is claimed is:

ll. A stacked resistor structure comprising:

a plurality of ribbon resistive elements of smooth helical twist, eachhaving a common axis of revolution and center,

said resistive elements arranged in intermeshing but non-contiguousrelationship with the common axes and centers of the plurality ofelements parallel; and

means for connecting said resistive elements to a source or" electricpotential whereby the elements may be interconnected in series,parallel, or series-parallel relationship.

2. A resistor structure as claimed in claim I in which the respectiveaxes of revolution of said resistive elements are coplanar.

3. A one-piece resistor structure comprising:

a plurality of ribbon portions of smooth helical twist, each having acommon axis of revolution and center, arranged in intermeshing butnon-contiguous relationship with the common axes and centers parallellyaligned, connected by bridge portions and initiating and terminating intab portions;

each of said port-ions being formed of resistive material; and

means on said tab portions for connecting the structure to a source ofelectric potential.

4. A resistor structure as claimed in claim 3 and further comprisingmeans on said bridge portions for connecting he structure to a source ofelectric potential, whereby the said helical ribbon twist portions maybe interconnected in series or parallel relationships.

5. A resistor structure as claimed in'claim 4 in which the respectiveaxes of revolution are coplanar.

6. A three-dimensional resistor structure comprising:

a first one-piece resistor structure comprising:

a plurality of ribbon portions of smooth helical twist, each having acommon axis of revolution and center, arranged in intermeshing butnon-contiguous relationship with the common axes and centers parallellyaligned, connected by bridge portions and initiating and terminating intab portions; second one-piece resistor structure comprising: pluralityof ribbon portions of smooth helical twist, each having a common axis ofrevolution and center arranged in intermeshing but non-contiguous relationship, with the common axes and centers parallelly aligned, connectedby bridge portions and initiating and terminating in tab portions; eachof said portions being formed of resistive material; said firstone-piece resistor structure and said second one-piece resistorstructure being juxtaposed in intermeshing but non-contiguousrelationship; and

means on said tab portions for connecting the structure to a source ofelectric potential.

A three-dimensional resistor structure comprising: first one-pieceresistor structure comprising:

a plurality of ribbon portions of smooth helical twist,

each having a common axis of revolution and center arranged, inintermeshing but non-contiguous relationship With the common axes andcenters parallelly aligned, connected by bridge portions and initiatingand terminating in tab portions;

a second one-piece resistor structure comprising: a plurality of ribbonportions of smooth helical twist,

each having a common axis of revolution and center, arranged inintermeshing but non-contiguous relationship With the common axes andcenters parallelly aligned, connected by bridge portions and initiatingand terminating in tab portions;

each of said portions of both grid resistors being the axes ofrevolution and of the plurality of ribbon formed of resistive material;

portions or" the first resistor structure being coplanar and the axis ofrevolution and center of the plurality of ribbon portions of the secondgrid resistor structure and being parallelly aligned in intermeshing butnon-contiguous relationship with the ribbon portions of the firstresistor structure; and

means on said tab portions for connecting the resistor structure to asource of electric potential.

8. A resistor structure as claimed in claim 7 and further comprisingmeans on at least one of the bridge portions for connecting the resistorstructure to a source of electric potential, whereby the plurality ofribbon portions may be interconnected in series or parallelrelationships.

9. A resistor structure as claimed in claim 6 and further comprisingmeans on the bridge portions for connecting the resistor structure to asource of electric potential, whereby the plurality of ribbon portionsmay be interconnected in series or parallel relationships.

References Cited by the Examiner UNITED STATES PATENTS RICHARD M. WOOD,Primary Examiner.

1. A STACKED RESISTOR STRUCTURE COMPRISING: A PLURALITY OF RIBBONRESISTIVE ELEMENTS OF SMOOTH HELICAL TWIST, EACH HAVING A COMMON AXIS OFREVOLUTION AND CENTER, SAID RESISTIVE ELEMENTS ARRANGED IN INTERMESHINGBUT NON-CONTIGUOUS RELATIONSHIP WITH THE COMMON AXES AND CENTERS OF THEPLURALITY OF ELEMENTS PARALLEL; AND MEANS FOR CONNECTING SAID RESISTIVEELEMENTS TO A SOURCE OF ELECTRIC POTENTIAL WHEREBY THE ELEMENTS MAY BEINTERCONNECTED IN SERIES, PARALLEL, OR SERIES-PARALLEL RELATIONSHIP.